Objective To study the prevalence and variation of influenza B viruses of Shenzhen. Methods Fifty strains influenza B viruses in Shenzhen from 1994 to 2006 were selected. HA1 gene were amplified by RT-PCR and sequenced. Phylogenetic analysis of HA1 was conducted by MEGA program. Results The influenza B viruses of Shenzhen were divided into Yamagata and Victoria lineage. The two lineages prevailed respectively in different years from 1994 to 2006. The variance of glycosylation site and some mutations of antigenic determinants were detected in the two lineages. Conclusion The viruses of Yamagata and Victoria lineage prevailed respectively in different years in Shenzhen but the mutation rates of the two lineages were slowly.

Objective To analyze the genetic characteristics of H1N1 influenza viruses isolated in Shenzhen during 1995 to 2007. Methods The hemagglutinin(HA) gene of these viruses were sequenced. Phylogenetic analysis of the sequences was performed with Simmonic and Mega software. Results The H1N1 influenza viruses isolated in Shenzhen from 1995 to 2007 were divided into chide A, B and C. Some viruses from 2005 to 2006 clustered in the same group with the viruses of 2001. Furthermore, some of the vaccine strains recommended by WHO were found lagged behind the strains isolated in Shenzhen. Some mu-tations occurred on the antigenic sites as well as receptor-binding site(RBS). Except the viruses of 1995, the other viruses had deleted at the site 137. Conclusion Characterization of the HA gene revealed that most of the amino acid substitutions occurred on the antigenic sites and RBS. Furthermore, it was discovered that the mutations occurred on different antigenic regions in different years.

Objective To analyze neuraminidase(NA) inhibitor resistance of seasonal H1N1 influenza A viruses isolated in Shenzhen during 2008 to 2009. Methods The NA gene of these viruses were sequenced. Phylogenetic analysis of the sequences was performed with Mega3. 1 software. Results In 2008, most isolates of the seasonal H1 N1 virus were susceptible to neuraminidase inhibitors, but the H275Y mutation in the neuraminidase gene region associated with high-level oseltamivir resistance had been detected in 92.6% of the strains isolated in 2009. Furthermore, a strain with Q136K was found, which showed the resistance to Zanamivir. Conclusion In the light of emerging resistance, close monitoring and understanding of the nature and dynamics of resistance mutations in influenza virus should be a priority.

Objective: To analyze the monitoring results and characteristics of human metapneumovirus (HMPV) outbreaks in Shenzhen in kindergartens and schools during 2017-2023, so as to provide a evidence for prevention and control of respiratory diseases. Methods: Based on the epidemiological data and laboratory test results of HMPV outbreaks in kindergartens and schools of Shenzhen during 2017 to 2023, collected from the influenza monitoring network platform, Mann Kendall test was applied for trend analysis pf HMPV. Results: A total of 11 HMPV outbreaks were identified in kindergartens and schools from 2017 to 2023 for 128 cases with an average incidence rate of 26.61% in 2018. The most yearly HMPV outbreaks were reported in 2020 being 4 outbreaks, followed by 2 outbreaks in 2018. A total of 72.73% (8 outbreaks) of HMPV outbreaks were identified in kindergartens with 27.27% (3 outbreaks) occurring in primary schools. The monthly greatest count of outbreak was 3(27.27%) in March and December, followed by 2 outbreaks (18.18%) in April and June. A total of 98 swab samples were collected, and 80 samples were positive for respiratory viruses with a positive rate of 81.63%; among them, 67 samples were positive for HMPV alone, 10 samples were positive for other respiratory viruses alone, and 3 samples were positive both for HMPV and other respiratory virus. Among the 11 human metalung virus cases, 6 HMPV outbreaks were caused by human metapneumovirus alone, and 5 outbreaks were caused by HMPV and other respiratory viruses. Except for 2020, the percentage of HMPV outbreaks in influenza like illness outbreaks increased with year ( Z=2.25, P =0.02). Conclusion HMPV outbreaks have been reported every year from 2017 to 2023 in kindergartens and schools in Shenzhen, most of HMPV in kindergartens, and the peak seasons of HMPV outbreaks are spring and winter.

Objective:To investigate the role and possible molecular mechanisms of m6A methyltransferase METTL3 and demethylase FTO in H7N9 virus infection.Methods:Western blot(WB) was used to detect the expression of METTL3 and FTO after H7N9 virus infected A549 cells. After knocking down and over-expressing METTL3 and FTO, H7N9 virus infection was tested by WB and TCID 50 for its effect on virus replication. Transcriptome sequencing method were used to analyze differentially expressed genes at the transcriptome level in METTL3 or FTO knockdown and wild-type control cells, and preliminary analysis of potential targets was performed. Results:After 24 h of H7N9 virus infection in A549 cells, METTL3 expression was up-regulated, and FTO did not significantly change. After knocking down METTL3 and FTO, the virus nucleoprotein (NP) expression level and virus titer decreased significantly. Consistent with the result of the knockdown experiments, we found that the viral titer was increased by METTL3 and FTO overexpression. Transcriptome sequencing result showed that 314 and 555 differentially expressed genes were found between the METTL3 or FTO knockdown group and the control group, respectively. GO functional enrichment analysis and KEGG pathway enrichment analysis showed that these genes were related to the host immune response.Conclusions:METTL3 and FTO may play a key role in H7N9 virus infection by regulating host-virus interactions.

Objective:To understand the epidemiological characteristics of human respiratory syncytial virus (HRSV) among cases presenting with influenza-like illness (ILI) in Shenzhen City from 2019 to 2023.Methods:Respiratory specimens were collected from two national sentinel hospitals in Shenzhen from March 2019 to December 2023, specifically targeting cases of ILI. The real-time PCR method was used for the detection and genotyping of HRSV. Basic demographic information was collected and used for the epidemiological analysis.Results:A total of 9 278 respiratory specimens of influenza-like cases were collected and detected, with a total positive rate of 4.77% (443/9 278) for HRSV. In 2021 (8.48%, 167/1 970), the positive rate of HRSV was significantly higher than in 2019 (3.35%, 52/1 552), 2022 (1.80%, 39/2 169), and 2023 (4.49%, 133/2 960), and the difference was statistically significant ( χ 2=102.395, P<0.001). The prevalence of HRSV was mainly in summer and early autumn (September), and there was an abnormal increase in the positive rate of HRSV in winter 2022. The highest positive rate of HRSV was in children under five years old (9.84%, 330/335). The typing results showed that in 2022, the prevalence of HRSV-A was predominant (71.79%, 28/39), and in 2023, HRSV-A and HRSV-B subtypes coexisted. Conclusions:The prevalence of HRSV in Shenzhen from 2019 to 2023 has obvious seasonality, mainly in summer and early autumn. Children under five years old are the main population of HRSV infections.

Objective:To understand the epidemiological characteristics of human respiratory syncytial virus (HRSV) among cases presenting with influenza-like illness (ILI) in Shenzhen City from 2019 to 2023.Methods:Respiratory specimens were collected from two national sentinel hospitals in Shenzhen from March 2019 to December 2023, specifically targeting cases of ILI. The real-time PCR method was used for the detection and genotyping of HRSV. Basic demographic information was collected and used for the epidemiological analysis.Results:A total of 9 278 respiratory specimens of influenza-like cases were collected and detected, with a total positive rate of 4.77% (443/9 278) for HRSV. In 2021 (8.48%, 167/1 970), the positive rate of HRSV was significantly higher than in 2019 (3.35%, 52/1 552), 2022 (1.80%, 39/2 169), and 2023 (4.49%, 133/2 960), and the difference was statistically significant ( χ 2=102.395, P<0.001). The prevalence of HRSV was mainly in summer and early autumn (September), and there was an abnormal increase in the positive rate of HRSV in winter 2022. The highest positive rate of HRSV was in children under five years old (9.84%, 330/335). The typing results showed that in 2022, the prevalence of HRSV-A was predominant (71.79%, 28/39), and in 2023, HRSV-A and HRSV-B subtypes coexisted. Conclusions:The prevalence of HRSV in Shenzhen from 2019 to 2023 has obvious seasonality, mainly in summer and early autumn. Children under five years old are the main population of HRSV infections.

Objective: Exploring the molecular characteristic of global and Shenzhen district H5N6 and H7N9 influenza viruses HA untranslated regions(UTRs). Methods: Mega7.0 and DNAStar 7.1.0 were used to construct phylogenetic tree and nucleotide analysis. Results: From 2014 to 2015, 3 strains of H5N6 influenza virus from Shenzhen were compared with the other H5NX influenza viruses, the nucleotide homology of HA-3’UTR was 77.4%-100%, which did not have obvious mutated sites. The nucleotide homology of H5N6-HA-5’UTR was 91.7%-100%, and the sites of 24 and 31 sites were mutated. From 2013 to 2014, 11 strains of H7N9 influenza virus from Shenzhen were compared with the other H7NX influenza viruses, the nucleotide homology of H7N9-HA-5’UTR was 76.8%-100%, which had multi-mutated sites on 2-6, 9, 10, 12 and 15-17 positions. Conclusions HA-UTR from human-infected H5N6 and H7N9 influenza viruses isolated in Shenzhen district has unique molecular characteristics, its conserved region has relatively high homology and the segment-specific region has genetic polymorphism.